Department of Radiology, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
Department of Radiology, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
Acad Radiol. 2024 Jun;31(6):2456-2463. doi: 10.1016/j.acra.2023.12.048. Epub 2024 Jan 18.
To compare image quality and metal artifact severity at 0.55 T and 1.5 T MRI in patients with spinal implants following posterior fusion surgery.
50 consecutive patients (mean age: 69 ± 12 years) who underwent 0.55 T and 1.5 T MRI following posterior fusion surgery of the lumbar or thoracolumbar spine were included. Examinations used metal artifact reduction protocols from clinical routine. Images were rated by two fellowship-trained musculoskeletal radiologists for image quality, ability to assess the spinal canal and the neural foramina, and artifact severity on 5-point Likert scales. Additionally, differences in artifact severity and visibility of near-metal anatomy among implant sizes (1-level vs. 2-level vs. >2-levels) were evaluated.
Signal/contrast (mean: 4.0 ± 0.3 [0.55 T] vs. 4.4 ± 0.6 [1.5 T]; p < .001) and resolution (3.8 ± 0.5 vs. 4.2 ± 0.7; p < .001) were rated lower at 0.55 T. The ability to assess the spinal canal (4.4 ± 0.5 vs. 4.2 ± 0.9; p = .69) and the neural foramina (3.8 ± 0.5 vs. 3.8 ± 0.9; p = .19) were however rated equally good with excellent interrater agreement (range: 0.84-0.94). Susceptibility artifacts were rated milder at 0.55 T (1.8 ± 0.5 vs. 3.0 ± 0.6; p < .001). For implant size-based subgroups, the visibility of near-metal anatomy decreased with implant length at 1.5 T, but remained unchanged at 0.55 T. In consequence, the spinal canal and neural foramina could be better assessed at 0.55 T in patients with multi-level implants (4.4 ± 0.5 vs. 3.6 ± 1.1; p < .001).
Metal artifacts of spinal implants are substantially less pronounced at 0.55 T MRI. When examining patients with multi-level posterior fusion, this translates into a superior ability to assess near-metal anatomy, where 1.5 T MRI reaches diagnostic limitations.
比较脊柱内植物后路融合术后患者在 0.55T 和 1.5T MRI 中的图像质量和金属伪影严重程度。
共纳入 50 例连续患者(平均年龄:69±12 岁),这些患者在接受腰椎或胸腰椎后路融合术后均接受了 0.55T 和 1.5T MRI 检查。使用临床常规的金属伪影降低方案进行检查。两位接受过肌骨放射学专科培训的放射科医生使用 5 分李克特量表对图像质量、椎管和神经孔的评估能力以及伪影严重程度进行评分。此外,还评估了不同植入物尺寸(1 级 vs. 2 级 vs. >2 级)之间的伪影严重程度和近金属结构的可见度差异。
0.55T 时的信号/对比(平均值:4.0±0.3[0.55T] vs. 4.4±0.6[1.5T];p<0.001)和分辨率(3.8±0.5 vs. 4.2±0.7;p<0.001)评分较低。椎管(4.4±0.5 vs. 4.2±0.9;p=0.69)和神经孔(3.8±0.5 vs. 3.8±0.9;p=0.19)的评估能力评分相当,具有极好的组内一致性(范围:0.84-0.94)。0.55T 时的磁化率伪影(1.8±0.5 vs. 3.0±0.6;p<0.001)评分较轻。基于植入物尺寸的亚组分析显示,1.5T 时近金属结构的可见度随植入物长度的增加而降低,但在 0.55T 时保持不变。因此,在多节段植入物的患者中,0.55T 时能更好地评估椎管和神经孔(4.4±0.5 vs. 3.6±1.1;p<0.001)。
脊柱内植物的金属伪影在 0.55T MRI 中明显较轻。在检查多节段后路融合的患者时,这可提高对近金属结构的评估能力,而 1.5T MRI 则达到诊断限制。